High pressure gerotor type hydraulic motors

ABSTRACT

This invention relates to hydraulic motors of the type which utilizes a rotary piston gear set, known as a gerotor, for forming expansible and contractible chambers. The invention resides in a valving and fluid passage arrangement wherein a rotating or orbiting valve is disposed in a fluid inlet chamber to which pressurized fluid is admitted. The pressurized fluid in the chamber forces the valve into sealing engagement with a valve block which has passages through which pressurized fluid is admitted to the expansible chambers. The fluid exhaust passages are arranged in the valve and valve block in a manner such that the engaging surfaces of the valve and valve block are the only relatively movable surfaces which separate the pressurized inlet fluid from the depressurized outlet fluid.

UnitedStates Patent 11 1 I 1 V 1 1 1 1 3,829,258

Easton 1 Aug. 13, 1974 HIGH PRESSURE GEROTOR TYPE 3,389,618 6/1968 McDermott 418/61 x HYDRAULIC MOTORS 3,405,603 10/1968 Woodling 418/61 R25,126 2/1962 Charlson 91/467 [76] Inventor: Wayne B. Easton, 17591 Kilmer Ave, Eden Prairie, Minn. 55343 [22] Filed: May 14, 1971 Primary Examiner-Irwin C. Cohen [21] Appl. No.: 143,618 [57] ABSTRACT Related US. Application Data This invention relates to hydraulic motors of the type [63] Continuation of Ser. N6. 670,962, Sept. 27, 1967, which 1 3 98 know" 5 a abandon gerotor, for forming expansible and contractlble chambers. The invention resides in a valving and fluid 52 11.8. C1. 418/61 B, l37/625.21 passage arrangement wherein a rotating or Orbiting 511 Int. Cl. F01C 1/02 valve, dispvsed in a fluid inlet chamber to which [58] Field of Search 418/61; l37/625.21 P r ed fluid is admitted The Pressurized fluid in 1 1 the chamber forces the valve into sealing engagement [5 References Cited I with a valve block which haspassages through which UNITED STATES PATENTS pressurized fluid is admitted to the expansible chambers. The fluid exhaust'passages are arranged in the 2532;: 3:33; valve and valve block ina manner such that the en- 1,489:396 4/1924 Odum 137/62521 gagmg f s h Valve and block are the 2,042,186 5/1936 Peterson 137/625.21 only relatlvely m v Surfaces Whlch Separate the 3,272,142 9/1966 Easton 418/61 Pressurized inlet fluid from the depressurized Outlet 3,288,034 11/1966 White, Jr. et a1. 418/61 fluid.

3,289,542 12/1966 F1156; 418 61 1 1 I 3,316,814 5/1967 Charlson 418561 14 Claims, 10 Figures 10 1 12 I as 43 I 9 1 44 %&18%

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HIGH PRESSURE GEROTOR TYPE HYDRAULIC MOTORS This application is a continuation of Ser. No. 670,962, filed Sept. 27, 1967, and now abandoned.

This invention relates to hydraulic motors of the type which utilize a gerotor.

Gerotor type hydraulic motors are well known in the art. A motor of this type usually has a separate valve for directing pressurized fluid from the inlet port to the gerotor and directing fluid exhaust by the gerotor to the outlet port. There are at least three types of valves used for such motors. One type of valve is rotatable in synchronism with the rotational movement of the star member of the gerotor. Another type of valve is rotatable in synchronism with the orbital movement of the star with the orbital movement of the star member. These valves all have the same basic function of feeding and exhausting fluid to and from the gerotor of the motor at the orbiting frequency of the motor.

At present the pressure limit for the operating fluid for gerotor type hydraulic motors is about 1200 psi although pressures of 1500 to 2000 psi would be highly desirable because of the increased torques which would result from the use of higher pressures. The main reason for the pressure limitation of about 1200 psi is that the inherent construction of prior art valves is such that short circuiting of substantial percentages of the supply fluid from the inlet port to the outlet port is prevalent.

A main object of the present invention is to provide a new and improved gerotor type hydraulic motor having a valve construction and arrangement in which short circuiting of the operating fluid is eliminated or at least minimized. Another object is to provide a new and improved valve construction and arrangement in which the pressure of the operating fluid itself is utilized to effect a more effective and efficient sealing arrangement for preventing or minimizing the short circuiting of the operating fluid.

Other objects and advantages will become apparent from the following specification, appended claims and attached drawings.

In the drawings:

FIG. 1 is a longitudinal fragmentary sectional view of a gerotor type hydraulic motor of the slow speed valve type embodying one form of the invention and taken on line l-1 of FIG. 2;

FIG. 2 is a transverse sectional view taken on line 2--2 of FIG. 1;

FIG. 3 is a transverse sectional view taken on line 3-3 of FIG. 1 (and line 3--3 of FIG. 4) except that a portion thereof is broken away to show the gerotor;

FIG. 4 is a longitudinal sectional view of a gerotor type hydraulic motor of the high speed valve type embodying a second form of the invention and taken on line 4-4 of FIG. 5;

FIG. 5 is a transverse sectional view taken on line 5--5 of FIG. 4;

FIG. 6 is a transverse sectional view taken on line 6--6 of FIG. 4;

FIG. 7 is a longitudinal fragmentary sectional view of a gerotor type hydraulic motor of the high speed orbiting valve type embodying a third form of the invention and taken on lines 7--7 of FIG. 9;

FIG. 8 is a transverse sectional view taken on line 8-8 of FIG. 7;

FIG. 9 is a transverse sectional view taken on line 9-9 of FIG. 7;

FIG. 10 is an end view of the crankshaft which is a part of the motor shown in FIG. 7.

It will be noted that FIGS. 2, 3, 5, 6, 8 and 9 do not show the corresponding drive shafts of FIGS. 1, 4 and 7. The reason for omitting the drive shafts in these views is because they are of conventional types and their omission actually makes the views from which they are ommitted easier to understand from the standpoint of the invention.

In the fluid pressure motor or pump illustrated in FIGS. 1 to 3 there is provided a casing or housing made of several cylindrically shaped sections which are a fluid inlet and valve chamber casing section 2, a valve block casing section 3, a gerotor casing section 4, a gerotor side plate 5 and a casing section 6 which houses driving means for connecting the gerotor to a drive shaft 7. Disk shaped end cover plate 8 and 9 are provided at opposite ends of the casing assembly. Casing sections 2 to 7 and the end plates 8 and 9 are held together in axial alignment by a plurality of circumferentially spaced bolts 10.

The shape of gerotor casing section 4 is generally cylindrical and annular (see FIGS. 1 and 3) and has a plurality of internal teeth. An externally toothed star member 12 having at least one fewer teeth than casing section 4, which may be referred to as a ring member 4, has the teeth thereof in meshing engagement with the teeth of ring member 4. Star member 12 has a hypocycloidal movement and travels in an orbit about the axis of the ring member 4.

Casing section 2 is cylindrically shaped and has an internal bore 13. Rotatably journalled in valve casing section 2 for rotation about the main axis 14 of the motor is a valve 15. Valve 15 is illustrated as having a cylindrically shaped cup portion 16 with a central bore 17 opening towards valve block 3 and a collar portion 18 which is journalled relative to and has a rotary sliding engagement with casing bore 13.

Valve block 3 has a central bore 20 which is in fluid communication with the adjacent valve bore 17. Valve collar 18 has a radially extending. annularly shaped surface 21 which is cooperable in rotational sliding engagement with the adjacent radially extending, annularly shaped surface 22 of valve block 3. The enclosure defined by valve block 3, casing section 2 and end plate 8 defines a valve chamber. The enclosure surrounded or defined by casing section 2, end plate 8 and valve 15 comprises an inlet chamber 23, and an inlet port 24 is provided in end plate 8 for admitting pressurized fluid to the inlet chamber 23. Pressurized fluid in inlet chamber 23 exerts a force on valve 15 proportional to the effective cross-sectional area thereof to bias the valve against valve block 3.

In each of the three embodiments of the invention the opening of the bore 20 in the surface 22 is separated from the inlet chamber by being covered by a valve and in this respect this opening of the bore 20'is deemed to be controlled by the valve.

With reference to FIG. 3, the gerotor casing section 4, which in effect is the ring member 4, has a plurality of internal teeth 26. Externally toothed star member 12, having at least one fewer teeth 27 than ring member 4, is disposed eccentrically in the chamber or space formed and surrounded by ring member 4. Star member 12 is moveable orbitally relative to the ring member 4 with the axis 28 of star member 12 being moveable in an orbital path about the axis 14 of ring member 4. During orbital movement of star member 12 the teeth 27 thereof intermesh with the ring member teeth 26 in sealing engagement to form expanding and contracting cells 29 which are equal in number to the number of teeth 27 of star member 12.

With reference to FIGS. 2 and 3, a vertical centerline 30 incidentally represents the line of eccentricity for the star member 12 for that particular position of the star member relative to the ring member 4. As used herein the term line of eccentricity means a line or plane which at all times intersects the ring and star axis 14 and 28 regardless of the position of star 12. The line of eccentricity 30, although it is an imaginary line, in effect rotates at the same speed that star 12 orbits relative to ring axis 14. During orbital movement of the star member 12, and assuming the orbital movement is clockwise, the cells 29 on the right side of the line of eccentricity 30 (as viewed in FIG. 3) would be contracting and the cells 29 on the left side would be expanding. In the operation of the motor, fluid under pressure is directed to the expanding cells and exhausted from the contracting cells. Bore 20 of valve block 3 is of small enough diameter so that the resulting annular face 31 which abuts gerotor ring member 4, along with gerotor side plate 5, form sides for the gerotor chamber so that the expanding and contracting cells 29 formed between the teeth of the gerotor star and ring members will be closed for all orbital positions of the star member.

Star member 12 has a bore 32 which is concentric relative to the teeth 27 thereof and the bore 32 is provided with a plurality of circumferentially arranged, axially extending teeth or splines 33. Bores 34 are provided in valve portion 16 into which is press fitted a pin 35 which extends diametrically across valve bore 17. A wobble shaft 36 extends through valve block bore 20 and mechanically connects star 12 and valve in driving relation. Heads 37 and 38 at opposite ends of shaft 36 are frustospherically shaped with head 37 being provided with splines which are equal in number to and mesh with splines 33 of the star and with head 38 being provided with a diametrically extending slot 39 for receiving the pin 35 to form a driving connection therebetween. Valve 15, by reason of the shaft connection between it and star 12, will rotate at the same speed as the star 12 but in the opposite direction from the orbiting direction of the star 12.

Star member 12 is eccentrically disposed relative to ring member 4, as mentioned above, and shaft 36 is thus always in a cocked or tilted position relative to valve 15, which has the same axis 14 as ring member 4, and to the axis 28 of star member 12. In operation a star member 12 having six teeth will make one revolution about its own axis 28 for every six times the star member orbits in the opposite direction about the axis 14 of the ring member 4. Thus, the head 37 of shaft 36 has both orbital and rotational movement in common with the star member 12 while the head 38 of the shaft has only rotational movement in common with valve 15. The illustrated connections between the opposite ends of shaft 36 with the star and valve members are forms of universal joints which permit the shaft 36 to have the motion described above. In the operation of the motor the force created by the rotation of star member 12 about its own axis 28 will be transmitted through drive means (not shown) to shaft 7 to cause turning of shaft 7. There are several known ways of transmitting the orbital or rotational movement of the star 12 to the shaft 7 and such drive means forms no part of the present invention.

Valve block 3 has an outlet 40 which extends radially from the bore 20 thereof to the exterior of the casing. Valve 15 and valve block 3 are provided with fluid pussages through which fluid is conveyed from the inlet port 24 to expanding cells 29 of the gerotor and fluid is exhausted from the contracting cells of the gerotor to the outlet port 40.

With reference to FIG. 2, valve 15 has a set of six axially extending feeding passages 41 which form six circumferentially spaced and arranged openings in the valve face 21 which have fluid communication with inlet chamber 23. Valve 15 also has a set of six axially extending exhausting passages 42 which form six circumferentially arranged and spaced openings in the valve face 21 which are alternately spaced relative to the openings of the passages 41 in the valve face 21. Exhausting passages 42 have fluid communication with exhaust port 40 through valve block bore 20, valve bore 17 and radially extending passages 43 which open into valve bore 17 and have respective fluid communication with axially extending passages 41.

Valve block 3 has a plurality of generally axially extending, circumferentially arranged and spaced passages 44 illustrated as being seven in number which is equal to the number of teeth 26 of the ring member 4. Passages 44 open into the radial face 22 of valve block 3 which is in sliding engagement with the radial face 21 of valve 15. Upon rotation of valve 15, each of the valve passages 41 and 42 successively registers in fluid communication with each of the valve block passages 44 in a known manner such that fluid is supplied to and withdrawn from the gerotor through valve block passages 44 which terminate at points which constitute junctions (see FIG. 3) between the teeth 26 of ring member 4.

In the operation of the motor, pressurized fluid is introduced through port 24 into the inlet chamber 23 from where it flows directly into valve passages 41 and then only through valve block passages 44 which are on the left side of the line of eccentricity 30 as viewed in FIG. 3 to the gerotor cells 29 on the left side of the line of eccentricity which are caused to expand by the pressurized fluid. The expansion of the cells 29 on the left side of the line of eccentricity 30 causes star 12 to orbit in a clockwise direction as viewed in FIG. 3 and causes collapsing of the cells 29 on the right side of the line of eccentricity 30. Fluid from the collapsing cells 29 flows out through valve block passages 44 which are on the right side of the line of eccentricity 30, as viewed in FIG. 3, through valve passages 42 and 43 on the left side of the line of eccentricity as viewed in FIG. 2, through valve bore 17 and valve block bore 20 and out outlet port 40. The line of eccentricity 30 rotates about the axis 14 of ring member 4 and, as long as pressurized fluid is admitted through inlet port 24, pressurized fluid will be always admitted to cells 29 on the same side of the line of eccentricity and fluid will always be exhaus'ted on the other side of said line.

During orbiting the star 12 about ring member axis 14, the star rotates in the opposite direction about its own axis 28 at a slower speed. The ratio between the orbiting and rotating speeds is dependent upon the ratio between the ring and star member teeth. If that ratio is 7 to 6 as illustrated herein, the rotating speed of the star will be one-sixth of its orbiting speed. By reason of the shaft connection between star 12 and valve 15, valve rotates at the same speed and in the same direction as star 12. Valve 15 is a commutating type valve in that it rotates at the same speed that star 12 rotates but it functions to supply and exhaust fluid to and from the gerotor at the orbiting frequency of the star. In the motor illustrated, the star orbits in a clockwise direction as viewed in FIG. 3 and, depending on the mechanical connection (not shown) between star 12 and drive shaft 7, the orbiting direction of the star determines the rotating direction of shaft 7. Normally with this type of motor a change in direction of the shaft 7 can be effected by simply reversing the inlet and outlet ports. Motor embodying the present invention do not permit this expedient, however, and the inlet and outlet ports thereof cannot be used alternatively to change the direction of rotation of the drive shaft 7.

If it is desired in the embodiment illustrated in FIGS. 1 to 3 the shaft 7 rotate in the opposite direction, it is necessary to change the indexing of valve 15 relative to the star 12. This may be accomplished by withdrawing wobble shaft 36 from its toothed engagement with star 12, rotating the shaft 30 in either direction and reinserting it. If the star 12 has 12 teeth or splines as illustrated, a one tooth displacement in either direction will effect the required angular displacement of 30.

A main advantage of the present invention is that there are no pressure limitations with regard to the operating fluid as far as the valve is concerned. In this connection it will be noted that pressurized fluid in inlet chamber 23 biases valve 15 against valve block 3 and no other mechanical means need be provided to control the axial positioning of valve 15. This is also true with respect to the second and third embodiments of the invention.

Valve surface 21 and valve block surface 22 are illustrated as being flat surfaces which must be smooth and true to avoid leakage from occuring anywhere between these surfaces and this is essential in prior art devices of this type as well as in the motors illustrated herein.

In the present invention, however, wear the results from the sliding engagement between surfaces 21 and 22 is automatically and continuously compensated for by reason of the pressurized fluid in inlet chamber 23 exerting a force which biases valve 15 towards valve block surface 22. There is no practical limit to the magnitude of the permissible pressure of fluid in inlet chamber 23 because the only possible path of escape or leaking between relatively moveable surface is the path between valve surface 21 and valve block surface 22. Leakage will not occur along this path, however, because, as the pressure increases, the pressure dependent force biasing the valve 15 against the valve block 3 also increases so as to press the surfaces 21 and 22 more tightly together and thus deters or precludes pressurized fluid from forcing its way between these surfaces. The exhausting of the fluid from the gerotor is separated from the feeding of fluid to the gerotor by the valve surfaces 21 and 22 and there is no possibility of short circuiting of the pressurized fluid to the exhaust passages except between surfaces 21 and 22. Surfaces 21 and 22 are inherently effective sealing surfaces, however, by reason of valve 15 being biased toward valve block 3 as explained above.

It may be mentioned at this point that it would also be within the scope of the invention for the surfaces 21 and 22 to be mutually engaging conically shaped surfaces in that wear occuring between conical surfaces would also be compensated for by reason of the biasing of valve 15 towards valve block 3.

The motor illustrated in FIGS. 4 to 6, which is a high speed valve type of motor, has several parts which are illustrated as being identical to corresponding parts of the motor shown in FIGS. 1 to 3 and will not be described in detail again. The parts of the motor of FIGS. 1 to 3 which are identical to corresponding parts of the motor in FIGS. 4 to 6 are the valve block 3, the gerotor ring member 4, the star member 12, the gerotor side plate 5, and the casing end plate 8. The parts of the second motor which are the same as corresponding parts of the first motor have the same reference numeralsassociated therewith. In FIG. 4 the transverse section 3-3 indicated is exactly identical to FIG. 3 and FIG. 3 will thus be referred to in connection with describing the motor of FIGS. 4 to 6.

In the motor illustrated in FIGS. 4 to 6 (and FIG. 3 by reference), there is provided a casing or housing made of several cylindrically shaped sections which are a fluid inlet and valve chamber casing section 50, a valve block casing section 3, a gerotor casing section 4, a gerotor side plate 5 and a casing section 51 which partially houses driving means for connecting the gerotor to a drive shaft 52. A disk shaped end cover plate 8 is provided at one end of the casing assembly where it is attached to valve casing section 50. Casing sections 50, 3, 4, 5 and 51 and the end plate 8 are held together in axial alignment by a plurality of circumferentially spaced bolts 53.

Casing section 50 is cylindrically shaped and has an internal bore 54. Rotatably journalled in valve casing section 50 for rotation about the main axis 14 of the motor is a disk shaped valve which is of somewhat lesser thickness than the axial length of casing section 50. Valve 55 has the same effective diameter as casing bore 54 and is journalled relative: to and has a rotary sliding engagement with casing bore 54. Valve 55 has a radially extending surface 56 which is cooperable in rotational sliding engagement with the adjacent radially extending, annularly shaped surface 22 of valve block 3. The enclosure defined by valve block 3, casing section 50 and end plate 8 defines a valve chamber. The enclosure surrounded or defined by casing section 50, end plate 8 and valve 55 comprises an inlet chamber 57, and an inlet port 24 provided in end plate 8 admits pressurized fluid to the inlet chamber 57. Pressurized fluid in inlet chamber 57 exerts a force on valve 55 proportional to the effective cross-sectional area thereof to bias the valve against valve block 3.

Casing section 51 has a bore 58 and a counterbore 59. Shaft 52 comprises a stub portion 60 and a shank portion 61. Shaft stub portion 60 extends through casing bore 58 and the shank portion 61 is journalled with respect to and in the casing counterbore 59. Shaft shank 61 has an axially extending bore 62 and gerotor plate 5 has a central opening 63, the bore 62 and the opening 63 being provided to accommodate the presence of a wobble shaft between star 12 and the drive shaft 52. Star member 12 has a bore 32 which is concentric relative to the teeth 27 thereof and the bore 32 is provided with a plurality of circumferentially arranged, axially extending teeth or splines 33. Bores 64 are provided in shaft shank 61 into which is press fitted a pin 65 which extends diametrically across the shaft shank bore 62. A wobble shaft 66 is provided which mechanically connects star 12 and shaft 52 in driving relation. Heads 67 and 68 of shaft 66 are frustospherically shaped with head 67 being provided with splines which are equal in number to and mesh with splines 33 of the star and with head 68 being provided with a diametrically extending slot 69 for receiving the pin 65 to form a driving connection therebetween. Shaft 52, by reason of the shaft connection between it and star 12, will rotate at the same speed as the star 12 but in the opposite direction from the orbiting direction of the star 12. The driving of shaft 52 by star 12 through wobble shaft 66 is completely analogous to the driving of the valve 15 in the first embodiment of the invention, which is explained above, and thus further explanation is not necessary.

Valve block 3 has an outlet 40 which extends radially from the bore thereof to the exterior of the casing. Valve 55 and valve block 3 are provided with fluid passages through which fluid is conveyed from the inlet port 24 to expanding cells 29 of the gerotor and fluid is exhausted from contracting cells of the gerotor to the outlet port 40. Valve block 3 has a plurality of generally axially extending, circumferentially arranged and spaced passages 44 illustrated as being seven in number which is equal to the number of teeth 26 of the ring member 4. Passages 44 open into the radial face 22 of valve block 3 which is in sliding engagement with the radial face 56 of valve 55.

With reference to FIGS. 5 and 6, valve 55 has an elongated slot 70 recessed relative to surface 56 which is utilized in cooperation with wobble shaft 66 for rotating the valve. Wobble shaft 66 has a portion thereof which extends from shaft head 67 through valve block 3 towards valve 55 and has a cylindrical shaped finger 71 at the end thereof. Finger 71 has a diameter equal to the Width of slot 70 and extends into the slot 70 in driving relation thereto. In operation the finger 70 has an orbiting movement relative to the axis 14 which is in synchronism with the oribiting movement of star 12 and hence the rotational movement of valve 55, resulting from the drive force of wobble shaft 66, is in synchronism with the orbital frequency of star 12. In effect, the slot 70 and the line of eccentricity rotate in unison about the axis 14 in synchronism with the orbiting movement of star 12 Valve 55 has an are shaped slot 72 on one side of the slot 70 which extends all the way through the valve from the valve surface 56 to the opposite valve surface 73. Valve 55 has a modified are shaped slot 74 on the other side of slot 70, slot 74 being recessed relative to the valve face 56 instead of extending through the valve as does slot 72. Slot 74 is referred to as being modified because it is formed with a bay 75. As can be seen in FIG. 6, the slot bay 75 overlaps valve block bore 20 so that slot 74 is at all times in fluid communication with valve bore 20 and the outlet port 40. On the other hand, slot 72 is at all times in fluid communication with the inlet chamber 57 and the inlet port 24.

Upon rotation of valve 55, valve slots 72 and 74 successively register in fluid communication with each of the valve block passages 44 in a known manner such that fluid is supplied to and withdrawn from the gerotor through valve block passages 44 which terminate at points which constitute junctions (see FIG. 3) between the teeth 26 of ring member 4.

In the operation of the motor illustrated in FIGS. 4 to 6, pressurized fluid is introduced through port 24 into the inlet chamber 57 from where it flows directly into the valve feeding slot 72 and through valve block passages 44 which are on the left side of the line of eccentricity 30 as viewed in FIGS. 3 and 6, to the gerotor cells 29 on the left side of the line of eccentricity which are caused to expand to the pressurized fluid. The expansion of the cells 29 on the left side of the line of eccentricity 30 causes star 12 to orbit in a clockwise direction as viewed in FIG. 3 and causes collapsing of the cells 29 on the right side of the line of eccentricity 30. Fluid from the collapsing cells 29 flows out through valve block passages 44 which are on the right side of the line of eccentricity as viewed in FIGS. 3 and 6 into the valve exhausting slot 74, and the bay 75, to valve block bore 20 and out outlet port 40. The line of eccentricity 30 rotates about the axis 14 of the ring member 4 and, as long as pressurized fluid is admitted through inlet port 24, pressurized fluid will always be admitted to cells 29 on the same side of the line of eccentricity and fluid will always be exhausted on the other side of the said line.

The shaft connection between star 12 and valve 55 causes valve 55 to be rotated at the same speed and in the same direction as the orbiting movement of star 12. Valve 55 is a distributing type valve in that it rotates at the same speed that star 12 orbits and functions to supply and exhaust fluid to and from the gerotor at the orbiting frequency of the star. In the motor illustrated in FIGS. 4 to 6, the orbiting direction of the star determines the rotating direction of shaft 52 which is opposite to the orbiting direction of the star. If it is desired to reverse the direction of rotation of shaft 52 it is necessary to change the indexing of valve 55 relative to the star 12. This may be accomplished by withdrawing valve 55 from its engagement with shaft finger 71, rotating the valve 180 and reinserting it. Slot is of sufficient length so that it can be installed in either of the two positions so that the desired direction of rotation for shaft 52 may be selected in this manner.

Valve surface 56 and valve block surface 22 are illustrated as being flat surfaces which must be smooth and true to avoid leakage from occurring anywhere between these surfaces. Wear that results from the sliding engagement between surfaces 56 and 22 is automatically and continuously compensated for by reason of the pressurized fluid in inlet chamber 57 exerting a force which biases valve 55 towards valve block surface 22. The only possible path of escape or leaking between relatively moveable surfaces in the motor is the path between valve surface 56 and valve block surface 22. Leakage will not occur along this path because, as the pressure increases, the pressure dependent force biasing the valve 55 against the valve block 3 also increases so as to press the surfaces 56 and 22 more tightly together and thus deters or precludes fluid in inlet chamber 57 from coming between these surfaces. The exhausting of the fluid from the gerotor is separated from the feeding of fluid to the gerotor by the valve surfaces 56 and 22 and there is thus no possibility of short circuiting of the pressurized fluid to the exhaust passages except between surfaces 56 and 22 which are inherently effective sealing surfaces by reason of valve 55 being biased toward valve block 3 as explained above.

The motor illustrated in FIGS. 7 to 9 has several parts which are illustrated as being identical to corresponding parts of the motor shown in FIGS. 1 to 3 and will not be described in detail again. The parts of the motor of FIGS. 1 to 3 which are identical to the corresponding parts of the motor in FIGS. 7 to 9 are the valve block 3, the gerotor ring member 4, the gerotor side plate 5, and the casing end plate 8. The parts of the third motor which are the same as corresponding parts of the first motor have the same reference numerals associated therewith.

In the illustrated motor in FIGS. 7 to 10 there is provided a casing or housing made of several cylindrically shaped sections which are a fluid inlet and valve chamber casing section 80, a valve block casing section 3, a gerotor casing section 4, a gerotor side plate and a casing section 81' which houses driving means for connecting the gerotor to a drive shaft 82. A disk shaped end cover plate 8 is provided at one end of the casing assembly where it is attached to valve casing section 80. Casing sections 50,3, 4, 5 and 81 and the end plate 8 are held together in axial alignment by a plurality of circumferentially spaced bolts 83.

An externally toothed star member 120 having at least one fewer teeth than ring member 4 has the teeth 127 thereof in meshing engagement with the teeth 26 of ring member 4. Star member 120 is identical to the star members 12 of the first two motors described except that it has a plain central bore 132 instead of a splined central bore.

Casing section 80 is cylindrically shaped and has an internal bore 84. Disposed in valve casing section 80 for orbital movement about the main axis 14 of the motor is a valve 85 which is of somewhat lesser thickness than the axial length of casing section 80. Valve 85 is shaped so that it has a radially extending, annularly shaped surface 86 which is cooperable in sliding engagement with the adjacent radially extending, annularly shaped surface 22 of valve block 3. The enclosure defined by valve block 3, casing section 80 and end plate 8 defines a valve chamber. The enclosure surrounded or defined by casing section 80, end plate 8 and valve 85 comprises an inlet chamber 87 and inlet port 24 provided in end plate 8 admits pressurized fluid to the inlet chamber 87. Pressurized fluid in inlet chamber 87 exerts a force on valve 85 proportional to the effective cross-sectional area thereof to bias the valve against valve block 3.

Star member 120 has a bore 132 which is concentric relative to the teeth 127 thereof. Valve 85 has a circular recess 88 for use in connection with exhausting fluid from the gerotor, as will be explained, and a central bore 89 of lesser diameter which is recessed relative to recess 88 but does not extend all the way through the valve 85. A crank shaft 90 extends through valve block bore 20 and mechanically connects star 120 and valve 85 in driving relation. Crank shaft 90 has three cylindrically shaped sections which are a section 91 having the same diameter as star bore 132 in which it is rotatably disposed, a section 92 of the same diameter as valve block bore 20 in which it is rotatably disposed, and a section 93 having an axis 94 and being of the same diameter as valve bore 89 in which it is rotatably disposed. Crank section 92, being rotatably mounted in valve block bore 20, is coaxial with respect to machine axis 14 and is rotatably about axis 14. Crank section 91 and 93 are both eccentric relative to section 92 a distance equal to the eccentricity of star 120 relative to ring member 4 but the axes 28 and 94 of sections 91 and 93 are displaced from each other relative to the machine axis I4. Crank section 92 is of lesser axial length than valve block bore 20 so that fluid communication between outlet port 40 and valve recess 88 is facilitated. Valve 85, by reason of the shaft connection between it and star 120, will orbit at the same speed as star and in the same direction, but is always displaced 90 from the position of the star axis 28 as is indicated at any instant by the position of the line of eccentricity 30.

As mentioned above, valve block 3 has an outlet 40 which extends radially from the bore 20 thereof to the exterior of the casing. Valve 85 and valve block 3 are provided with fluid passages through which fluid is conveyed from the inlet port 24 to expanding cells 29 of the gerotor and fluid is exhausted from contracting cells of the gerotor to the outlet port 40. Valve block 3 has a plurality of generally axially extending, circumferentially arranged and spaced passages 44 illustrated as being seven in number which is equal to the number of teeth 26 of the ring member 4. Passages 44 open into the radial face 22 of valve block 3 which is in sliding engagement with the annular surface 86 of valve 85.

The diameter of valve 82 is substantially equal to the outside diameter of the ring of passages 44 in valve block 3. The width of the annular surface 86 of the valve is equal to the diameter of each of the valve block passages 44.

During the orbiting movement of valve 85 the passages 44 are successively uncovered by the valve to place them in fluid communication with pressurized fluid in the inlet chamber 87 to supply pressurized fluid to the gerotor, and the passages 44 are likewise successively exposed to the exhausting recess 88 of the valve to exhaust fluid from the gerotor.

In the operation of the motor illustrated in FIGS. 7 to 10, pressurized fluid is introduced through port 24 into the inlet chamber 87 from where it flows directly into valve block passages 44 which are on the left side of the line of eccentricity 30 as viewed in FIGS. 8 and 9 to the gerotor cells 29 on the left side of the line of eccentricity which are caused to expand by the pressurized fluid. The expansion of the cells 29 on the left side of the line of eccentricity 30 causes star 120 to orbit in a clockwise direction and causes collapsing of the cells 29 on the right side of the line of eccentricity 30. Fluid from the collapsing cells 29 flows out through valve block passages 44 which are on the right side of the line of eccentricity 30, through valve recess 89, valve block bore 20 and out outlet port 40. The line of eccentricity 30 rotates about the axis 14 of the ring member 4 and, as long as pressurized fluid is admitted through inlet port 24, pressurized fluid will always be admitted to cells 29 on the same side of the line of eccentricity and fluid will always be exhausted on the other side of said line.

The shaft connection between star 120 and valve 85 causes valve 85 to be orbited at the same speed and in the same direction as the orbiting movement of star 120. Valve 85 is a distributing type valve in that it orbits at the same speed that star 12 orbits and functions to supply and exhaust fluid to and from the gerotor at the orbiting frequency of the star. In the motor illustrated in FIGS. 7 to 10, the orbiting direction of the star determines the rotating direction of shaft 82. If it is desired to reverse the direction of rotation of shaft 82 it is necessary to change the indexing of valve 85 relative to the star 120. This may be accomplished by substituting a modified crankshaft for the crankshaft 90. With reference to FIGS. 8 and 10, the modified crankcase would the same as the the crankshaft illustrated except that the section thereof corresponding to crank section 93 would be displaced 180 from section 93 relative to the machine axis 14. if the modified crankshaft were installed, valve 85 would still be displaced 90 from the line of eccentricity 30 but in the opposite direction.

Valve surface 86 and valve block surface 22 are flat surfaces which must be smooth and true to avoid radially directed leaking between these surfaces. Wear that results from the sliding engagement between surfaces 86 and 22 is automatically and continuously compensated for by reason of the pressurized fluid in inlet chamber 87 exerting a force which biases valve 85 towards valve block surface 22. The only possible path of escape or leaking between relatively moveable surfaces is the path between valve surface 86 and valve block surface 22. Leakage will not occur along this path because, as the pressure increases, the pressure dependent force biasing the valve 85 against the valve block 3 also increases so as to press the surface 86 and 22 more tightly together and thus deters or precludes pressurized fluid in inlet chamber 87 from coming between these surfaces. The exhausting of the fluid from the gerotor is separated from the feeding of fluid to the gerotor by the valve surfaces 21 and 22 and there is no possibility of short circuiting of the pressurized fluid to the exhaust passages except between surfaces 86 and 22 which are inherently effective sealing surfaces by reason of valve 85 being biased toward valve block 3 and explained above.

What I claim is:

1. A fluid pressure operated motor comprising a casing, an internally toothed ring gear having a fixed axis, a cooperating externally toothed star gear having fewer teeth than said ring gear disposed eccentrically relative to the axis of said ring gear, said star gear having 360 rotational movement about its own axis and 360 orbital movement about the axis of said ring gear with the teeth of said gears intermeshing in sealing engagement to form expanding cells on one side ofthe line of eccentricity and contracting cells on the other side of said line during relative movement between said gears, a valve block fixedly attached to said ring gear, said valve block having a central opening, said valve block having a transversely extending surface axially spaced from said gears, fluid passages in said valve block extending from said block surface to said cells, said casing defining a valve chamber adjacent said valve block, an inlet port having fluid communication with said valve chamber, a valve in said valve chamber having a first surface thereof in slidable abutting and sealing engagement with said valve block surface, said valve having a second surface, said second surface being a side of said valve opposite from said first surface, said second surface being entirely axially spaced from the walls of said valve chamber, said valve being biased towards said valve block by pressurized fluid in said valve chamber acting on said second surface, said inlet port being the only opening for said chamber other than valve controlled openings in said valve block surface, drive means between said star gear and said valve for moving said valve so that said valve moves in synchronism with and has the same kind of movement as one of said movements of said star gear, said drive means extending through said valve block central opening, said valve cooperating with said valve block passages to continuously provide feeding of pressurized fluid from said valve chamber to said expanding cells, said valve having exhaust passage means cooperating with said valve block fluid passages to continuously exhaust fluid from said contracting cells, said valve exhaust passage means having the entrance thereto in said valve face and the exit therefrom in constant fluid communication with said valve block central opening, and an outlet port in said valve block having direct and constant fluid communication with said valve block central opening.

2. A fluid pressure operated motor in accordance with claim 1 wherein said valve has drive connecting means recessed relative to said valve first surface for engaging said drive means to effect driving of said valve.

3. A fluid pressure operated motor in accordance with claim 1 wherein said engaging valve and valve block surfaces are planar surfaces.

4. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said rotational movement of said star gear, said valve having circumferentially arranged fluid feeding passages intersecting said valve surfaces which are cooperable with said valve block passages, said fluid feeding passages extending through said valve and being in fluid communication with said inlet port.

5. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said rotational movement of said star gear, said valve having alternately and circumferentially arranged fluid feeding and fluid exhausting passages intersecting said first valve surface which are cooperable with said valve block fluid passages, said fluid feeding passages extending through said valve and being in constant fluid communication with said inlet port, said fluid exhausting passages forming a portion of said exhaust passage means.

6. A fluid pressure operated motor in accordance with claim 5 wherein said valve has a central bore recessed relative to said first valve surface and in axial alignment with said central opening of said valve block, said fluid exhausting passages of said valve being in fluid communication with said recessed central bore of said valve.

7. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said orbital movement of said star gear, said valve having fluid feeding passages means intersecting said first valve surface and being cooperable with said valve block passages, said valve being indexed relative to said drive means so that said fluid feeding passages means is on one side of said line of eccentricity, said fluid feeding passage means extending through said valve and being in fluid communication with said inlet port.

8. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said orbital movement of said star gear, said valve having fluid feeding and exhausting passage means intersecting said first valve surface on opposite sides of said line of eccentricity which are cooperable with said valve block passages, said valve being indexed relative to said drive means so that said fluid feeding and exhausting passage means are on opposite sides of said line of eccentricity, said fluid feeding passage means extending through said valve, said fluid exhausting passage means forming a portion of said exhaust passage means.

9. A fluid pressure operated motor in accordance with claim 1 wherein said fluid exhausting passage means in said valve is recessed relative to said valve first surface and is in overlapping relation to said central opening of said valve block to provide fluid communication therebetween.

10. A fluid pressure operated motor in accordance with claim 1 wherein said valve has an elongated slot recessed relative to said valve first surface for receiving one end of said drive means to effect rotation of the valve and index the valve relative to said star gear, said valve being l80 displaceable relative to said drive means to effect a reversal of the direction of operation of said star gear.

11. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effect an orbital movement of said valve in synchronism with said orbital movement of siad said gear, said fluid passages in said valve block defining a plurality of circumferentially arranged openings in said valve block surface equally spaced from said ring axis, said valve being generally circular in shape and having sliding engagement with said valve block surface, said valve being of a selected diameter so that during orbital movement of said valve said fluid passages in said valve block are sequentially exposed to pressurized fluid in said valve chamber which is directed to said expanding cells.

12. A fluid pressure operated :motor in accordance with claim 1 wherein said drive means effect an orbital movement of said valve in synchronism with said orbital movement of said star gear, said fluid passages in said valve block defining a plurality of circumferentially arranged openings in said valve block surface equally spaced from said ring axis, said valve being generally circular in shape and having an annularly shaped collar in sliding engagement with said valve block surface, said collar defining recessed fluid exhausting passage means within the conflnes of said collar, said col lar being dimensioned so that during orbital movement of said valve said fluid passages in said valve block are sequentially exposed to pressurized fluid in said inlet chamber which is directed to said expanding cells and said fluid passages in said valve block are sequentially connected to said recessed fluid. exhausting passage means to provide fluid communication between said contracting cells and said fluid outlet port, said recessed fluid exhausting passage means forming a portion of said valve exhaust passage means.

13. A fluid pressure operated motor in accordance with claim 1 wherein said outlet port and said fluid exhausting passage means in said valve having fluid communication with said central opening of said valve block.

14. A fluid pressure operated motor in accordance with claim 1 wherein said recessed fluid exhausting passage means is recessed relative to said first valve sur face and is in overlapping relation to said central opening of said valve block to provide fluid communication therebetween. 

1. A fluid pressure operated motor comprising a casing, an internally toothed ring gear having a fixed axis, a cooperating externally toothed star gear having fewer teeth than said ring gear disposed eccentrically relative to the axis of said ring gear, said star gear having 360* rotational movement about its own axis and 360* orbital movement about the axis of said ring gear with the teeth of said gears intermeshing in sealing engagement to form expanding cells on one side of the line of eccentricity and contracting cells on the other side of said line during relative movement between said gears, a valve block fixedly attached to said ring gear, said valve block having a central opening, said valve block having a transversely extending surface axially spaced from said gears, fluid passages in said valve block extending from said block surface to said cells, said casing defining a valve chamber adjacent said valve block, an inlet port having fluid communication with said valve chamber, a valve in said valve chamber having a first surface thereof in slidable abutting and sealing engagement with said valve block surface, said valve having a second surface, said second surface being a side of said valve opposite from said first surface, said second surface being entirely axially spaced from the walls of said valve chamber, said valve being biased towards said valve block by pressurized fluid in said valve cHamber acting on said second surface, said inlet port being the only opening for said chamber other than valve controlled openings in said valve block surface, drive means between said star gear and said valve for moving said valve so that said valve moves in synchronism with and has the same kind of movement as one of said movements of said star gear, said drive means extending through said valve block central opening, said valve cooperating with said valve block passages to continuously provide feeding of pressurized fluid from said valve chamber to said expanding cells, said valve having exhaust passage means cooperating with said valve block fluid passages to continuously exhaust fluid from said contracting cells, said valve exhaust passage means having the entrance thereto in said valve face and the exit therefrom in constant fluid communication with said valve block central opening, and an outlet port in said valve block having direct and constant fluid communication with said valve block central opening.
 2. A fluid pressure operated motor in accordance with claim 1 wherein said valve has drive connecting means recessed relative to said valve first surface for engaging said drive means to effect driving of said valve.
 3. A fluid pressure operated motor in accordance with claim 1 wherein said engaging valve and valve block surfaces are planar surfaces.
 4. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said rotational movement of said star gear, said valve having circumferentially arranged fluid feeding passages intersecting said valve surfaces which are cooperable with said valve block passages, said fluid feeding passages extending through said valve and being in fluid communication with said inlet port.
 5. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said rotational movement of said star gear, said valve having alternately and circumferentially arranged fluid feeding and fluid exhausting passages intersecting said first valve surface which are cooperable with said valve block fluid passages, said fluid feeding passages extending through said valve and being in constant fluid communication with said inlet port, said fluid exhausting passages forming a portion of said exhaust passage means.
 6. A fluid pressure operated motor in accordance with claim 5 wherein said valve has a central bore recessed relative to said first valve surface and in axial alignment with said central opening of said valve block, said fluid exhausting passages of said valve being in fluid communication with said recessed central bore of said valve.
 7. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said orbital movement of said star gear, said valve having fluid feeding passages means intersecting said first valve surface and being cooperable with said valve block passages, said valve being indexed relative to said drive means so that said fluid feeding passages means is on one side of said line of eccentricity, said fluid feeding passage means extending through said valve and being in fluid communication with said inlet port.
 8. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effects rotation of said valve in synchronism with said orbital movement of said star gear, said valve having fluid feeding and exhausting passage means intersecting said first valve surface on opposite sides of said line of eccentricity which are cooperable with said valve block passages, said valve being indexed relative to said drive means so that said fluid feeding and exhausting passage means are on opposite sides of said line of eccentricity, said fluid feeding passage means extending through said valve, said fluid exhausting passage means forming a portion of said exhaust passage means.
 9. A fluid pRessure operated motor in accordance with claim 1 wherein said fluid exhausting passage means in said valve is recessed relative to said valve first surface and is in overlapping relation to said central opening of said valve block to provide fluid communication therebetween.
 10. A fluid pressure operated motor in accordance with claim 1 wherein said valve has an elongated slot recessed relative to said valve first surface for receiving one end of said drive means to effect rotation of the valve and index the valve relative to said star gear, said valve being 180* displaceable relative to said drive means to effect a reversal of the direction of operation of said star gear.
 11. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effect an orbital movement of said valve in synchronism with said orbital movement of siad said gear, said fluid passages in said valve block defining a plurality of circumferentially arranged openings in said valve block surface equally spaced from said ring axis, said valve being generally circular in shape and having sliding engagement with said valve block surface, said valve being of a selected diameter so that during orbital movement of said valve said fluid passages in said valve block are sequentially exposed to pressurized fluid in said valve chamber which is directed to said expanding cells.
 12. A fluid pressure operated motor in accordance with claim 1 wherein said drive means effect an orbital movement of said valve in synchronism with said orbital movement of said star gear, said fluid passages in said valve block defining a plurality of circumferentially arranged openings in said valve block surface equally spaced from said ring axis, said valve being generally circular in shape and having an annularly shaped collar in sliding engagement with said valve block surface, said collar defining recessed fluid exhausting passage means within the confines of said collar, said collar being dimensioned so that during orbital movement of said valve said fluid passages in said valve block are sequentially exposed to pressurized fluid in said inlet chamber which is directed to said expanding cells and said fluid passages in said valve block are sequentially connected to said recessed fluid exhausting passage means to provide fluid communication between said contracting cells and said fluid outlet port, said recessed fluid exhausting passage means forming a portion of said valve exhaust passage means.
 13. A fluid pressure operated motor in accordance with claim 1 wherein said outlet port and said fluid exhausting passage means in said valve having fluid communication with said central opening of said valve block.
 14. A fluid pressure operated motor in accordance with claim 1 wherein said recessed fluid exhausting passage means is recessed relative to said first valve surface and is in overlapping relation to said central opening of said valve block to provide fluid communication therebetween. 